1. Field of the Invention
The present invention is directed to a method and an apparatus for a mast assembly wherein the mast raising cylinders will be nested in a box-type substructure for transportation and storage. In particular, the present invention is directed to a method and apparatus for a mast assembly which improves assembly and disassembly time and facilitates transportation thereof.
2. Related Art
Drilling rigs used to explore for subterranean oil and gas are traditionally moved to a desired drilling site. The rig equipment is then assembled and the drilling or servicing operation performed. After the drilling or servicing operation has been completed, the equipment is traditionally disassembled piece by piece and moved to another drilling or servicing site and reassembled. The equipment may be transported on dollies or flatbed tractor trailers.
The time and required personnel to assemble the drilling rig and thereafter to disassemble and transport the drilling rig to another location is an important factor in the overall expense of the drilling operation.
One type of drilling rig utilizes a mast or derrick assembly having a lower mast section, a center mast section mounted on top of the lower mast section, and an upper mast section mounted on top of the center mast section. In one arrangement, each mast section includes a pair of opposed sides, a back face and an open front. The opposed sides include braces, trusses or supports. The open front facilitates entry and removal of lengths of tubulars. A crown block on top of the upper mast section facilitates reciprocal vertical movement of a moving block and tackle and other drilling equipment. A pair of hydraulic cylinders moves the lower mast section, center mast section and upper mast section from a horizontal storage and transportation position to a vertical operational position during the assembly and the disassembly procedure.
Various equipment is located on a drill or drilling floor which is often elevated from ground level so that additional equipment, such as a blowout preventer, may be installed beneath the drill floor. A substructure or substructures elevate the drill floor above ground level.
It is a principal object and purpose of the present invention to improve the assembly or rig up time and effort and improve the disassembly or rig down time and effort required.
It is a further object and purpose of the present invention to eliminate disconnection of the cylinders from the substructure during the disassembly procedure so that the cylinders are stored and transported along with the substructure.
Additionally, it would be advantageous for the equipment to be moved to meet roadway requirements for size of load. For example, certain highway regulations limit the width of the load to twelve feet. Highway regulations may also limit the height of the load.
Accordingly, it is a further object and purpose of the present invention to minimize disassembly and reassembly of the mast assembly while permitting transportation on flat bed trailers.